Study of Ti deposition onto Al alloy by cold gas spraying

The Cold Gas Spray method has become a novel thermal-spray process which offers an amount of interesting advantages such as no oxidation and dense coatings; it involves the acceleration of the powder particles by injection into a high-velocity gas stream and these are then impinged upon suitable substrates. Common consensus says that the main parameter that controls the process is the critical particle velocity ( v c), above which, the particles are able to adhere and form the coating; v c depends mainly on the material composition, particle size and substrate materials. In the present work, the influence of the propellant gas temperature and pressure and, of the powder feeding rate has been studied for the deposition of titanium powder onto aluminium substrates by Cold Gas Spray. Different sets of parameters have been tested in order to optimize the process regarding porosity and adherence of the deposits. The interest arose as a way to protect the aluminium alloy 7075-T6, highly used in aeronautic engineering, from corrosion. It has been also studied as an alternative to other deposition techniques such as Electrodeposition, Chemical Vapour Deposition and Vacuum Plasma Spray, which are more expensive.